During the second period of this grant focus has been on the facile production and use of short-lived positron emitting nuclides with special emphasis on fluorine-18 and compounds labeled with fluorine-18. Furthermore efforts to make these methods available to a larger community of scientists and to engage in increased off-site collaboration have been effected. In addition a number of projects involving iodine-123 were continued, the preparation of nitrogen-13 labeled compounds (e.g. N13-Amphetamine), the preparation of N13-NH3 from the oxides of nitrogen and the preparation of the carbon-11 labeled synthetic precursor (e.g. C11-phosgene) were studied, as was the preparation of other compounds labeled with short-lived nuclides. The preparation of anhydrous fluorine-18 in high specific activity was effected by the development of new targetry, a new radioactive gas handling system, and a study of the excitation function of the Ne20(d, alpha)F18 reaction. At the present time up to 1.2 Curies of anhydrous F18-F2 are routinely produced as needed at specific activities well in excess of 10,000 Curies/mol utilizing high pressure targetry and incident currents of up to 20 microamperes. Fluorine from this target was used to prepare F18-2-deoxy-2-fluoro-D-glucose via a new synthetic route. This research material was utilized in vivo in a collaborative study with the University of Pennsylvania. Anhydrous fluorine-18 was also used to prepare F18-5-fluorouracil which was used in tumor uptake studies. The labeled sugar may be of use in studying the dynamics of regional brain metabolism. Plans for the coming year include continued in improving fluorine-18 production and utilization of anhydrous fluorine-18 in preparing labeled compounds, research on the biochemistry and application to medical problems of carbon-11 labeled amines, further development of nitrogen-13 chemistry and that of other short-lived positron emitting nuclides, and continued efforts in iodine-123 preparation and chemistry. Collaborative efforts with other institutions in research and application will hopefully continue to be expanded.